1. Field of the Invention
The present invention relates to an electric water pump in which a Hall IC can be mounted on a circuit substrate at an optimum position in a stable and durable state.
2. Description of the Related Art
Following recent advances in development of electric and hybrid vehicles, the number of electric water pumps installed on the vehicles has increased. Most of the electric water pumps that are presently used are the so-called integrated electric water pumps in which a section having a motor function and a section having a pump function are integrated together. The integrated electric water pump has disposed therein a stator constituted by a coil and a stator core serving as a motor stator, an inner magnet serving as a motor rotor, and an impeller integrated with the inner magnet. The magnetic force of the stator is controlled by controlling the energizing of the coil, and the inner magnet is rotated continuously and smoothly.
Since the stator is fixed and the inner magnet rotates, a relative angle of magnetic poles of the stator and magnetic poles of the inner magnet change with the passage of time. Further, a magnetic force of a certain predetermined value is generated in the stator at a certain predetermined relative angle of the magnetic poles of the stator and the magnetic poles of the inner magnet, thereby rotating the inner magnet continuously and smoothly. A Hall IC is generally widely used as a means for detecting a position (phase) of the magnetic poles of the inner magnet in the angular direction from time to time and measuring the orientation and intensity of magnetic field by measuring the intensity of magnetic field of the inner magnet in order to attain such smooth and continuous operation.